How can we form residential broadband?

This is an article: read it and change it! Really hard to find!

The website of the resource is: A report about "Campus Network Entering Dormitory" in Tsinghua Campus News Online may be helpful! The paper is just a patchwork! I think so! Ha ha!

In recent years, with the adjustment of telecom tariffs, the start of government internet access project, the deepening of enterprise network construction boom and the application of e-commerce, it can be expected that a new round of internet access boom is coming. Coupled with the further development of network applications and the emergence of new business types represented by interactive applications such as video on demand (VOD), video conferencing and online shopping, users have put forward higher requirements for the speed of data communication. As the "last mile" in the network system, access network is attracting more and more attention. However, due to various reasons, the user's access rate can not meet the needs of multimedia applications. For this reason, a new generation of high-speed access technologies such as ADSL and Cable Modem have been put on the stage and exposed frequently. ?

This paper mainly introduces ADSL technology. On the one hand, ADSL technology is based on the existing twisted-pair copper wire, which is more economical and easier to realize under the current actual situation in China, and is expected to become the next generation mainstream user access mode; On the other hand, because the telecom departments in most cities in China don't support ADSL technology (only experiments of ADSL technology have been carried out in Shenzhen, Shanghai and Beijing), we only provide a campus network solution based on ADSL technology. ?

1.What is the development background of ADSL technology?

With the continuous development of network technology, especially the rapid development of Internet, people pay more and more attention to access technology. In the past few years, access technology based on copper wire has made rapid development, including access using V-series modems and xDSL technology. It is the simplest and most economical way to access the network through telephone line (twisted pair copper wire) by using modem, but it is limited by the speed of modem. Despite people's continuous efforts, the speed of modem keeps rising from the initial 2.4kbit/s, and has experienced 9.6kbit/s, 14.4kbit/s, 28.8kbit/s and 33.6kbit/s successively. However, due to the limited frequency band (3400Hz) used by V-series modems, it is almost impossible to continue to speed up. Then, on the existing copper wire, how to further improve the network access rate? Various DSL (Digital Subscriber Line) technologies become the best solution. ?

Among many DSL technologies, ADSL technology is more representative, which can update the application scope of Internet access, such as video on demand (VOD? Open? Demand) and conference call, etc. , has practical significance. Below, we will make a brief introduction on ADSL technology. ?

The working principle of 2.2. Asymmetric Digital Subscriber Line

ADSL (Asymmetric Digital Subscriber Line) is called Asymmetric Digital Subscriber Line in Chinese. When ADSL modems are placed at both ends of a telephone line, three information channels are generated on this telephone line: one with the rate of 1.5Mbps? 9Mbps high-speed downlink channel for users to download information; 16kbps rate? 1Mbps medium-speed duplex channel; An ordinary old-fashioned telephone service channel; And these three channels can work at the same time. (Of course, the specific communication rate also depends on the quality and length of the line. Generally speaking, the effective transmission distance is within the range of 3-5 kilometers. You can download files and watch video programs online without affecting the use of your mobile phone. The most important thing is that all this is done at the same time on a telephone line. ?

What does ADSL rely on to achieve all this? Speaking of it, the inside of ADSL is very complicated. It uses advanced digital signal processing technology and new algorithms to compress data, so that a large amount of information can be transmitted at high speed on the Internet. We know that it is very serious to transmit data on the existing copper twisted pair (ordinary telephone line), and it is difficult for ADSL to achieve large dynamic range, separate channels and maintain low noise interference in such a harsh environment. No wonder some people say that ADSL is a miracle of modem technology. ?

In order to separate the effective bandwidth on the telephone line and generate multiple channels, ADSL modems generally adopt two methods, frequency division multiplexing (FDM) or echo cancellation technology. FDM allocates one frequency band in the existing bandwidth as the data downlink channel and the other frequency band as the data uplink channel. The downlink channel is subdivided into a plurality of high-speed channels and low-speed channels by time division multiplexing (TDM) technology. Similarly, the uplink channel is also composed of multiple low-speed channels. Echo cancellation technology makes the uplink and downlink frequency bands overlap, and the two frequency bands are distinguished by local echo cancellation. This technology comes from V.32 and V.34 modems. It uses the limited bandwidth very effectively, but it is expensive in complexity and price. Of course, no matter which of the two technologies is used, ADSL will separate the 4kHz frequency band for POTS. ?

At present, ADSL modem equipment mostly adopts three line coding technologies, which are called carrier amplitude and phase suppression (carrier? Small amplitude and phase, CAP), discrete multitone, DMT) and discrete wavelet multitone, DWMT). CAP is based on quadrature amplitude modulation (QAM), which modulates data onto a single carrier. In DMT, data is modulated onto multiple carriers, and the data on each carrier is modulated by QAM. In DMT, the well-known fast Fourier transform algorithm is used for digital signal processing, while in DWMT, the emerging wavelet transform algorithm is used to replace the fast Fourier transform. An ADSL modem combines the data streams in multiple downlink channels, duplex channels and maintenance channels into blocks, and adds an error correction code to each block, and the receiver corrects the error code generated in the transmission process through this error correction code. Experiments show that this error correction coding technology can completely reach MPEG? 2 and other digital image compression methods. ?

Asymmetric Digital Subscriber Line (ADSL) is mainly different from the previous modem technology in that its uplink and downlink rates are asymmetric, that is, the uplink and downlink rates are not equal. The high downlink rate and relatively slow uplink rate of ADSL technology are very suitable for Internet/Intranet browsing. ?

3. What are the characteristics of 3.ADSL?

1)ADSL has a data rate unmatched by V-series modems. ?

2)ADSL technology is based on twisted-pair copper wire, so ADSL has a broad application base. There are 700 million telephone copper wires in the world. In China, the scale of telephone network has jumped to the second place in the world, among which the program-controlled ratio is as high as 99.7%, which provides a good foundation for the application of ADSL technology in China. ?

3)ADSL technology is cost-effective. ADSL technology uses twisted-pair copper wire of traditional telephone network, which can realize voice transmission and data transmission storage on the same twisted-pair copper wire without laying another transmission line, thus greatly saving the cost. ?

4) Compared with cable modems, ADSL has the characteristics of exclusive bandwidth. Although CATV network can realize high bandwidth of multimedia transmission, when the number of Internet users increases, the bandwidth owned by each user will drop sharply because of its * * * bandwidth. ADSL is based on telephone copper wire, and each user has exclusive bandwidth, which will not be affected by the increase in the number of Internet users. ?

5) 5) The uplink and downlink rates of ADSL are asymmetric. The high downlink rate and relatively slow uplink rate of ADSL technology are very suitable for Internet/Intranet browsing. ?

4. What equipment does 4.ADSL need?

On the user side, ADSL modem needs to be installed. The user's computer is connected to the ordinary telephone line through a modem. ADSL modem has a chip for signal separation called POTS filter. The signal from the telephone line is divided into two paths through it, one for transmitting voice and the other for transmitting data. The signal transmitting data will pass through the channel separator and be divided into two channels: uplink and downlink. ?

The equipment of the exchange office is DSLAM (Digital Subscriber Line Access Multiplexer), which is used to connect ADSL users to the high-speed backbone network. There is also an ADSL modem and a POTS filter in front of the DSLAM equipment in the exchange office, so the signal at the user end is divided into two paths after passing through the ADSL modem. One way is voice signal, which is sent to the PSTN (Public Switched Telephone Network) equipment of the exchange office, and the other way is used to transmit data, which is sent to the DSLAM equipment and transmitted to the backbone network through the DSLAM equipment. Generally speaking, DSLAM devices are connected to ATM networks.

5.ADSL application scope

ADSL has a wide range of applications, mainly including the following aspects:

1) distance teaching?

Through ADSL broadband network, campuses located in different regions can form an online virtual campus, which is convenient for distance teaching. ?

Television broadcast?

Through ADSL broadband network, video and audio signals can be transmitted at high speed, which is convenient for TV broadcast. ?

Shopping online?

Through ADSL broadband network, you can browse goods quickly and watch clear pictures, video introductions and audio of goods.

Explain. With the help of banks and credit card institutions, you can buy the goods and services you need online. ?

Community information release?

Residential property can put all kinds of information on the network through ADSL broadband network, and there is no need to issue various notices separately. For example:

Shopping guide, real estate quotation, reference materials, tourism services, film and television information, property charge notice, securities information, etc. ?

Video on demand?

VOD is video-on-demand, which is an interactive operation. It can order different kinds of videos through the network according to users' own preferences and needs.

B-type video program, watch it on the computer. You can also use the video output function of the graphics card on the computer to pass the S? build

Watch it on big screen TV and home theater. ?

Video conference?

Through ADSL broadband network connection, it is very easy to conduct real-time video conference with high quality and sound quality.

Love. ?

[hs2] [ht5 "h] 6 〓 ADSL technology application solution? 「HT5」SS

Taking a university as an example, this paper explains how to use ADSL technology to realize the establishment of multimedia LAN. ?

1) System status?

A university consists of three campuses?

A. Has a campus network been established in foreign campuses?

B. west campus, has the campus network been built?

C. East campus, no campus network?

Distance teaching and conference network is formed between the three campuses through DDN interface. ?

The problem to be solved now is the construction of campus network in East Campus. There are many schemes to build a campus network. Let's look at them here.

See how to use ADSL technology to solve this problem. ?

2) System objectives and functions?

First of all, let's analyze the existing equipment in the East Campus:

*+communication line?

The school has an internal telephone network, and almost all departments and cadres above the division level are equipped with extensions. Make use of existing ones

Combining lines to build a campus can save cost and manpower. If you want to expand in the future, you can use your own technical strength to complete it. ?

*+Computer and hardware resources?

The school has a computer center, multiple voice classrooms and multimedia classrooms, and all departments are equipped with computers, printers,

Scanners and other hardware equipment, multimedia classrooms are also equipped with projectors, physical booths and so on. ?

*+Audio-visual equipment?

The school has an audio-visual education center, equipped with cameras, video recorders, tape recorders and audio-visual editing equipment. According to the specific situation of the school

[fl] [lm] pss2, +58mm. 123mm, BP [medium? "Flight Level (K2)"

Situation, set the system goals as short-term goals and long-term goals. ?

Short-term goals?

Using the existing equipment in East Campus (mainly internal telephone network), a campus network based on ADSL technology is established, which mainly realizes

:?

Video conference?

Realize video conference on campus network. Teaching staff can be in their own offices or even at home (family dormitory in the north campus of the school).

You can attend the meeting. ?

Multimedia teaching?

To realize multimedia teaching on campus network, students can take classes in classrooms or dormitories, which can save various teaching resources (such as teaching

Rooms, equipment, teachers, etc. ).？

Office automation?

Realize office automation on campus network, so as to further realize "paperless" office. ?

Video on demand?

Computer cooperation?

Realizing collaborative design and collaborative writing on campus network. ?

Other?

Realize the functions of sending and receiving e-mail and BBS in multimedia LAN. ?

If the above functions can be realized, the following objectives can be achieved:

*4 resources * * * Enjoy?

Realize the enjoyment of venues and equipment, and greatly improve the utilization rate of school resources. ?

*4 Alleviate the contradiction of insufficient teachers?

*4 improve office efficiency?

*4 Make the East Campus and its student dormitories and family dormitories form a digital community. ?

Long-term goals

The first step is to realize the network interconnection of three campus networks by using DDN. ?

The second step is to use ADSL (which is generally supported by telecom in the future) to realize the network interconnection of three campus networks. ?

3) System design and network structure?

Initially decided to use ADSL technology to establish the campus network of the East Campus for the following reasons:

You can use the school's existing internal telephone lines and equipment. The advantage of this is that it can not affect the use of the original telephone.

Provide the function of interconnection and internet access under the conditions; ?

Each user has exclusive bandwidth, and the download rate is relatively high, which is more suitable for local video conference, video on demand and computer teaching.

Learning, digital community needs; ?

Because of the bright future of ADSL, if China Telecom supports ADSL technology, the existing network based on ADSL technology can be more inclusive.

Easily support broadband remote services. ?

Of course, using the existing telephone system to build a campus network based on ADSL technology requires some transformation of the original telephone system.

This conversion is divided into client and switch. ?

The only change in the customer telephone system is the addition of a filter and an ADSL modem. For the original telephone line

No change is needed. One end of the ADSL modem is connected to the DSL signal from the filter, and the other end is connected to the hub.

Or a switch (network switch). If the computer accesses the internal computer, it can be accessed through the HUB; If you visit the outside

First through the hub, then through the ADSL modem. ?

Add a proxy server running proxy server software. Computers in this network can access the Internet. ?

The switch of the school computer room is handled as follows:

The transformation of the exchange room is to add a filter to separate ADSL high-frequency signals before they enter the telephone exchange.

High-frequency ADSL signal is sent to ADSL modem, and telephone signal is sent to switch. The model diagram of access is shown in figure 1. 「FL」？

[〖CRS3, BP]?

Figure 〓 1

〖FL(K2〗〓〓

The whole network is divided into the following parts:

Academic orchid?

Mainly used for the management of students, teachers and teaching materials. ?

Financial LAN?

Library LAN?

Mainly used for books and periodicals procurement, cataloging, retrieval, lending and other management. ?

Central LAN?

It is mainly used to provide and manage various resources and provide various services for users. ?

The structure of the whole network is shown in Figure 2. 「FL」？

[〖CRS4, BP]?

[ht5 "h] [JZ (] Figure 〓 2 [JZ]]

「HT5」SS

[FL (K2) [HT5 "H] 7 〓 Conclusion? [KH-* 2]? 「HT5」SS

Because ADSL technology is not very mature, there is no unified standard, and China Telecom does not support it, so we just base on it.

This paper briefly discusses the construction of campus network based on ADSL technology. I hope there must be something wrong, even wrong.

The reader gives criticism and correction. 「FL」？

[ht][hs(7)[ht2bs][JZ(] Internet/Intranet technology in the office? Automation application [JZ]]

「HS」？

[ht4 "k] [JZ] Wang Huisen Wei?

[ht5 "f] [JZ] (Tianjin Institute of Navigation Instruments) 〓 (School of Mechanical Engineering, Hebei University of Technology)?

〓hk40 〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓 1230

This paper expounds the main features and technical keys of developing an automated office system by using modern Internet/Intranet technology.

And the construction process. ?

["HT5Y3"] Keywords 〓 〓〓ht5「k〓 K 〓 Office Automation 〓 Internet 〓 Intranet 〓 Application System

『HK』『HT』？ 「HT5」SS「FL(K2)」

[hs2] [ht5 "h] 1 〓 Preface [ht5" ss]?

Office Automation System Based on LAN and Computer Network

There are many kinds of office automation systems established under the network environment. For example, Clie can be developed and adopted using various relational database tools.

The software system with nt/Server structure can realize office automation, and can also be based on document database tools (such as Lotus Notes).

) Develop a transactional office system. Although these systems have their own advantages (mature technology and stable performance, etc.). ), if they wish.

I hope that I can meet the dual needs of the company's internal (LAN) office and the group's (WAN) office at the same time.

The office system exposes insurmountable weaknesses, either because of too much investment (such as applying for a special line) or because of applying for a venue.

Decentralized, the client program maintenance is inconvenient. In view of this, how to seize the opportunity of the great development of Internet/Intranet technology?

Using Internet/Intranet technology to develop a new generation of office automation system has become an important concern of all relevant departments.

Theme. ?

[HS2] [HT5 "h] 2 〓 Main features of office automation [HT5" SS]?

No matter what kind of office automation software system we develop, we need to know exactly what office automation is.

What aspects and contents are included? It is generally believed that all kinds of daily affairs and information processing in the office are in the main body of the office-

Under the control of people, it is done automatically by using modern tools and means, which is office automation. From multi-level and complex information processing

As far as heterogeneity is concerned, office automation can be divided into the following three levels or stages:?

1) word processing automation?

The main content is the process of receiving, reviewing and processing all kinds of documents transmitted by vertical and horizontal units; Our company sends the above list.

The process of drafting, reviewing and publishing documents; The formation of various reports, plans, summaries and other materials formed within the unit.

And the process of gradual examination and approval; Document integration and comprehensive file management. ?

2) transaction automation?

Its main contents include various administrative affairs (vehicle management, fixed assets management, etc.). ); Secretarial services (adjustment of meeting arrangements)

The whole, meeting notice, leadership activities planning, information editing, etc. ); Supervision affairs (led by affairs inspectors and letters and visits workers)

Management, etc. ); Professional affairs (human resource management, financial management, production and operation management, etc.). ); Personal affairs (personal letters

Information exchange, special discussion, personal address book, etc. ).？

3) Assistant decision-making automation?

This degree of automation is based on the first two aspects of automation, specifically for the person in charge to summarize all aspects of information, but for

All kinds of problems provide accurate, comprehensive and timely basis for correct decision-making. Its main content should be based on leadership synthesis.

Under the query platform, the information provided is mainly the summary and analysis of internal funds, operations and talents;

Analysis and prediction of related situations in international and domestic related fields; Classified compilation and quick reference of relevant national laws and regulations. By synthesis

Inquiry can make the leaders of the unit automatically and quickly obtain all kinds of detailed materials needed for decision-making, and make decision-making more timely and accurate.

[hs2] [ht5 "h] 3 〓 Structure of computer network office automation system [ht5" ss]?

The effective way to realize automatic network office depends on the relevant software products available at present.

along with

The following briefly introduces the construction of several network office automation systems based on popular market software. ?

3. 1 client/server architecture?

This office automation system is based on LAN environment, and its most representative development and use environment is as follows: in WIN NT Bureau.

The domain runs on the network, the client is developed by Powerbuilder or VB, VC, V FOX and other tools, and the server is developed by PowerBuilder.

Large relational databases, such as SQL SERVER, ORACLE, INFOMIX, SYBASE, etc. Centralized data processing. ?

3.2 transaction process system?

The system is also an office automation software based on LAN, and a transactional office system is developed using Lotus Notes.

The whole software runs on nt, NOVELL and Notes platforms, and its data processing mode also adopts Clien.

T/Server structure, but its background (server) is not the traditional large-scale relational database, but Notes.

The only document database. This kind of software is best at dealing with transactional work such as sending and receiving files?

3.3 System based on Internet/Intranet?

At present, the latest office automation system is based on Internet/Intranet environment, with simple operation and rich functions.

Run a universal browser, which is suitable for integrated office automation of cluster office inside and outside the unit. With the development of the internet

It is popular and will become the mainstream of office automation system in the new century with its rapid development. on the internet

Using browser to develop office automation system on /Intranet can directly use mature e-mail technology on the Internet.

Technology, information collection ability, infinitely extensible information nodes and browser interface format have been widely used.

Widely accepted, most users can operate quickly without obstacles. ?

Office Automation System Based on Internet/Intranet?

4. 1 architecture of application system?

The design and development of an automated office system based on Internet/Intranet is fundamentally

Is to establish an application system platform suitable for the characteristics of their own enterprises and institutions. It is strongly recommended to adopt internationally advanced clients-

Application server-database server three-tier architecture, as shown in figure 1. Use the browser as the main tool of the client.

Access server-side resources, including database servers. The browser here should have personalized adaptability and In.

Ternet/Intranet is the general front end of resource location and management, which can realize seamless connection and access to the database.

, and cooperate with the server to provide complete access control and confidentiality. The application server has Internet-related functions.

It also integrates the functions of firewall and proxy, which not only supports the creation and release of information at the client, but also supports office work.

File filling, publishing and streaming, and corresponding to the browser, to achieve a complete security management and protection system. 「FL」

〗

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[HT5 "h] [JZ] Figure 1〓Internet/Intranet application system architecture [HT5" SS]? 〖FL(K2〗〓〓

4.2 What are the basic methods to establish an automated office system?

The basic way to develop and establish a network office automation system based on Internet/Intranet is to build it in the unit.

Set up an intranet, set up your own WEB server, and connect with the external Internet through a "firewall".

Answer the phone. On the WEB server of the internal Intranet, a large database is established to store and manage all kinds of information inside the company.

Its application program can be developed with V JAVA, POWER JAVA, CGI, etc. , and installed on the WEB server. And users

Workstations only need to install a browser, and they can log in to the intranet to handle office affairs through the browser, and they will be in the office when necessary.

Automation software can directly (authorize) access to the external Internet to obtain the required information. At the same time, within the group,

When users in different places of the Ministry or personnel in the unit go out, they can also directly access the WEB services in the unit through the internet in different places.

Server (authorized), handling office affairs. ?

4.3 What are the characteristics of the automated office system based on Internet/Intranet?

The office automation system based on Internet/Intranet has its unique advantages, mainly including:

1) Support real off-site work?

Although the traditional office automation system has its advantages in some aspects, it is generally limited to the local area network within the unit.

Use, remote use can only be through remote login, which is neither safe nor easy to make mistakes, and no one uses it in actual work; In ...

The most outstanding advantage of office automation system in the form of ternet/Intranet is that it supports working in different places and meets the needs of industrial systems.

In principle, the offices of enterprise groups and even multinational groups can be like the internal offices of units as long as they have computers with Internet access.

Workstation, convenient to handle office affairs, at the same time, "firewall" technology can ensure the security of information and data.

At this point, other office systems are absolutely dwarfed. ?

2) Low cost?

The office automation system based on Internet/Intranet involves not only the construction of network environment and the purchase of application software.

In addition to the expenses of other office systems, it is no longer necessary to purchase any application platform for software operation, and it is no longer necessary.

Compared with all other office systems, the extra system resources generated by running the application software platform need to pay extra fees.

Comparatively, this method is the cheapest. ?

3) Simple operation?

Compared with the different user interfaces of other office systems, the Internet/Intranet office automation system

Using a unified well-known browser interface, you can start the application system without special operation, and you are used to making it.

Users who use the browser can operate without barriers even if they are not trained. Because people have preconceived habits, others

No matter how friendly the system interface is, there will be no browser mode operation that will be quickly accepted by users. ?

4) Rapid localization?

The system uses a combination of user-defined process and user-configurable free process to handle office affairs, so the software is commercialized.

In localization, users of different transaction processes can modify the process themselves without modifying the program. ?

5) Easy maintenance?

Because all the functional applications of the office automation system based on Internet/Intranet are on the WEB server, we use.

There is no program related to the operation function at the user end, and the user's business content changes or software failure needs to be modified and marked.

In order to ensure time, you only need to modify and maintain the software on the WEB server, away from other departments that may be distributed in the unit.

It has nothing to do with foreign client computers, and even the development company can't go to the site to maintain this system software.

Real remote maintenance can be realized through the Internet, which greatly reduces the maintenance cost of the system. ?

A conclusion?

With the continuous development of information construction and the progress of information port construction in major cities in China, the application of Internet will be realized.

Until people pay more attention to it, in the next decade, the Internet may become an information exchange between units, social groups and individuals.

, the main way of communication, with the help of Internet/Intranet office automation system, it is convenient to communicate with the Internet.

Various application systems are connected to form a cross-century office system. With the acceleration of the pace of information construction, with the Internet information

With the continuous enrichment of sources, its functions and information management scope will also be expanded, which will give people the concept of office and actors.

Types bring new changes. 「FL」？

〔HS2〕JZ〔CDH 03344〕

[FL (K2) [HT5 "H] (continued from page 38) 〓 [HT5" SS]

Setup can query the desktop properties of the computer to determine whether Windows Setup has installed the application. ?

[hs2] [ht5 "h] 4 〓 Making package file (. msi) [ht5" ss]？

A major feature of Windows installation technology is that you can make your own installation package files. If you do it a little soft.

Chess, you can make a (. Msi) package file, with which you can install your masterpiece on windows2000. that

How to do this package file? There are currently two tools available. One is Orca: the lowest level provided by Microsoft.

Tool, what you actually do is to fill in various table groups including: file table group, registry group, system table group, kernel table group,

References:

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